Answer
$\frac{1}{6}(e^{12}-1) $
Work Step by Step
Let $ u= 3y^2$, then $ du=6ydy $ and $ u $ takes the values from $0$ to $12$; hence we have
$$
\int_0^2 ye^{ 3y^2} dy=\frac{1}{6}\int_0^{12} e^{ u} du\\
=\frac{1}{6}\left[e^{u}\right]_0^{12}=\frac{1}{6}(e^{12}-1)
.
$$